Analog to digital convertors are well known in the art. Such convertors typically operate by dividing an operating input voltage range into a plurality of segments. A resultant binary signal can then be provided that relates to the number of segments that correspond to the magnitude of an actual input analog signal sample.
For optimum resolution of the digitizing process, the input voltage range should have some general correspondence to the general operating range of the incoming analog signal. For example, an analog signal that varies between 0 and 5 volts would not necessarily be well represented in digital form if digitized with respect to an input voltage range of 0-25 volts. Instead,.better resolution would generally result if the input voltage range were also 0-5 volts.
To meet this need, many analog to digital convertors have at least one range control input. Such an input allows the user to select the input voltage range. For some prior art convertors, the user may select from two or more preselected ranges by pin selection. In other convertors, maximum and minimum range inputs are provided such that the range can be selected over a relatively wide continuum.
For many applications, the above provisions are not adequate. For example, in digital signal processing, one determines certain signal attributes relative to the signal itself, instead of comparing the signal to some fixed predetermined value. Using prior approaches in this context can lead to reduced resolution and possible errors.
A need therefore exists for a means of ensuring adequate resolution during a digitization process while simultaneously accommodating fluctuations in the incoming signal.